title: Delay in leaf senescence of Malus hupehensis by long-term melatonin application is associated with its regulation of metabolic status and protein degradation.
abstract: Melatonin has an important anti-aging role in plant physiology. We tested the effects of long-term melatonin exposure on metabolic status and protein degradation during natural leaf senescence in trees of Malus hupehensis Rehd. The 2-month regular supplement of 100 μm melatonin to the soil once every 6 days altered the metabolic status and delayed protein degradation. For example, leaves from treated plants had significantly higher photosynthetic activity, chlorophyll concentrations, and levels of three photosynthetic end products (sorbitol, sucrose, and starch) when compared with the control. The significant inhibition of hexose (fructose and glucose) accumulation possibly regulated the signaling of MdHXK1, a gene for which expression was also repressed by melatonin during senescence. The plants also exhibited better preservation of their nitrogen, total soluble protein, and Rubisco protein concentrations than the control. The slower process of protein degradation might be a result of melatonin-linked inhibition on the expression of apple autophagy-related genes (ATGs). Our results are the first to provide evidence for this delay in senescence based on the metabolic alteration and protein degradation.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Xun
authors.initials: X
authors.lastname: Sun
authors.forename: Cong
authors.initials: C
authors.lastname: Chang
authors.forename: Fengjuan
authors.initials: F
authors.lastname: Feng
authors.forename: Dong
authors.initials: D
authors.lastname: Liang
authors.forename: Lailiang
authors.initials: L
authors.lastname: Cheng
authors.forename: Fengwang
authors.initials: F
authors.lastname: Ma
mesh_terms: D027845:Malus / Q000187:drug effects* / Q000378:metabolism*; D008550:Melatonin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000187:drug effects* / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D008550:Melatonin
keywords: Malus; Rubisco; autophagy-related genes; leaf senescence; melatonin; nitrogen; sugar